1. Technical Field
The present invention relates generally to a system and method for measuring image quality, and more specifically relates to measuring image quality using JPEG DCT coefficient information.
2. Related Art
In order to reduce processing costs, banks and other institutions are seeking to store and process more and more paper documents, including checks, as electronic images. New proposed laws are furthering this movement by, for example, allowing banks to transfer only the check images and associated data for downstream processing. This reduces the requirement for a bank to physically handle and forward paper checks after they are initially received and processed at the bank. However, such scenarios place significant responsibilities on the bank for the integrity of the data and the quality of the images, since the paper checks will not be available to downstream operations.
Because banks are expected to process and exchange thousands of items each day, a fast, automated system for measuring image quality is necessary to ensure that an acceptable image gets captured from each paper document. Various techniques exist for measuring image quality. For instance, U.S. Pat. No. 4,888,812, Document Image Processing System, Issued on Dec. 19, 1989, which is hereby incorporated by reference, discloses the monitoring of image data by determining if an acceptable gray scale distribution, and therefore image quality, exists. After the image is tested, the image is compressed and stored.
Furthermore, in some systems, the image quality must be tested after the image is compressed. Using known techniques, this requires the image to first be decompressed. Because compression protocols, such as JPEG, are relatively lossy, the decompressed image may have artifacts that can lead to compromises in any image quality measurement.
In general, image quality can be measured by examining and quantifying parameters such as the brightness, contrast and/or focus of the image. However, quantifying these parameters from a gray scale image requires significant computational resources. Moreover, because such tests must occur along with compression and decompression routines, providing a fast and efficient system remains an ongoing challenge.
Accordingly, a need exists for a system that can measure image quality with a high degree of accuracy and in a computationally efficient manner.